refactor(tags): improve tag operation planning and execution (#32)

tests/tags.test.ts

@@ -0,0 +1,37 @@
+/**
+ * Unit tests for tag operation execution, src/tags.ts
+ */
+import { jest } from '@jest/globals'
+import * as core from './fixtures/core.js'
+import * as github from './fixtures/github.js'
+
+// Mocks should be declared before the module being tested is imported.
+jest.unstable_mockModule('@actions/core', () => core)
+jest.unstable_mockModule('@actions/github', () => github)
+
+// The module being tested should be imported dynamically.
+const { executeTagOperation } = await import('../src/tags.js')
+import type { TagOperation } from '../src/tags.js'
+
+describe('executeTagOperation', () => {
+  beforeEach(() => {
+    jest.resetAllMocks()
+    github.getOctokit.mockReturnValue(github.mockOctokit)
+  })
+
+  it('throws error for unknown operation type', async () => {
+    const invalidOperation = {
+      operation: 'invalid',
+      name: 'v1',
+      ref: 'main',
+      sha: 'abc123',
+      owner: 'test-owner',
+      repo: 'test-repo'
+    } as unknown as TagOperation
+
+    await expect(
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      executeTagOperation(invalidOperation, github.mockOctokit as any)
+    ).rejects.toThrow('Unknown operation type: invalid')
+  })
+})